Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. Within the heart, the ability to control the exact position and orientation of the catheter tip is critical and largely determines how useful the catheter is.
The Seldinger technique is a medical procedure for insertion of heart catheters including central venous catheters. It is named after Dr. Sven-Ivar Seldinger (1921-1998), a Swedish radiologist. The technique involves puncturing the vein and inserting a guiding sheath, a guidewire and a dilator into the patient, as is generally known in the art. The dilator is removed, and a catheter is introduced through the guiding sheath whereby a guidewire lumen in the catheter allows the catheter to pass over the guidewire. The guidewire is then removed. For devices not having a guidewire lumen, the guidewire is removed prior to insertion of the device to allow passage. Once the distal end of the catheter reaches the desired location, the guiding sheath is withdrawn to expose the distal end of the catheter which may comprise an electrode assembly for mapping and/or ablation and any other structures to stabilize the electrode assembly in the heart or against the heart wall and tissue. Fluoroscopy may be used to confirm the position of the catheter and to maneuver it to the desired location. Injection of radiocontrast may be used to visualize organs. The sheath may be used for both right-sided procedures, and transseptal electrophysiologic procedures that require puncturing of the septum.
Bidirectional catheters have been designed to be deflectable in one direction by one puller wire and in the opposite direction within the same plane by a second puller wire. In such a construction, the puller wires extend into opposing off-axis lumens within the tip section of the catheter. So that the tip section can bend in both directions in the same plane, the puller wires and their associated lumens are located along a diameter of the tip section. Such catheters typically have a control handle at their distal end which have a thumb knob and/or a rotatable grip that is manipulated by an electrophysiologist to position catheter distal end at the desired location and/or operate electrode assemblies, such as contraction, expansion, deployment, retraction, etc.
Deflectable sheaths are also known, however, the deflection mechanism rotates around the axis of the control handle which facilitates two-handed manipulation but is not ideal for single-handed deflection. Thus, the operator cannot simultaneously deflect the sheath and the catheter extending through the sheath. Existing sheaths also use a soft distal tip with an embedded marker band which does not allow for optimal visualization of the most distal tip and does not provide extensive tip flexibility. Moreover, existing sheaths utilize a consistent cross-sectional profile along the longitudinal axis of the deflectable section which does not allow for changing of stiffness properties near the distal end.
Accordingly, it is desirable to provide a sheath introducer that has bidirectional deflection and a control handle that allows an operator to manipulate with one hand so he can simultaneously operate the control handle of the catheter extending through the sheath introducer. It is also desirable to provide a shaft, and more specifically a deflectable section of the sheath introducer, with sections of different durometer so that flexibility and softness varies near the distal end of the shaft, and in particular, with increased flexibility and softness toward the distal tip of the shaft. It is further desirable that the distal tip be radiopaque for optimal visualization and that the distal tip forms a seal with the catheter or device extending through the shaft so that minimal force is used during punctures and risk of distal tip prolapsing is reduced.